I usually have SO in running in several tabs on my browser, one tab for each tag I want to see questions listed for.
In tab one I may have the newest C++ questions:
And in another tab I may have the newest Python questions. Now, when I go to the C++ tab, and switch from newest questions to active questions
and then go back to my Python tab and hit F5 (or refresh for the non-PC guys), the page will jump to active Python questions after the refresh. Oops?
Also notable: if I manually switch back to newest Python questions, and go back to the C++ tab, this will not happen again, until I close all SO tabs and visit the page again. Then it is reproducable.
For reference, I am using Firefox 24.0.